A fuel system is the component of an internal combustion engine which often has the greatest impact on performance and cost. Accordingly, fuel systems for internal combustion engines have received a significant portion of the total engineering effort expended to date on the development of the internal combustion engine. For this reason, today's engine designer has an extraordinary array of choices and possible permutations of known fuel system concepts and features. Design effort typically involves extremely complex and subtle compromises among considerations such as cost, size, reliability, performance, ease of manufacture, and retrofit capability on existing engine designs.
The challenge to contemporary designers has been significantly increased by the need to respond to government mandated emissions abatement standards while maintaining or improving fuel efficiency. In view of the mature nature of fuel system designs, it is extremely difficult to extract both improved engine performance and emissions abatement from further innovations in the gasoline fuel system art. In response, the world's automakers have made significant investment in search of viable alternative fuel vehicles. Hydrogen powered vehicles are considered to be the most promising long-term automotive option, operating very efficiently while producing very little or no vehicle emissions. However, the environmentally friendly hydrogen currently does not have a distribution infrastructure capable of supplying consumers. Developing a viable distribution infrastructure could take years, with consumers in rural areas being the last to receive availability.
Therefore, commercially competitive fuel injection systems of the future will not only need to incorporate new design features for better achieving various objectives including improved engine performance and emissions abatement, but form a system capable of utilizing hydrogen as well as gasoline to effectively and reliably achieve the greatest number of objectives.
Improved efficiency, quick response and effective reliable injection rate are critical features for achieving objectives such as improved engine performance and emissions abatement. Other important features include packaging flexibility for installation on various engine configurations including retrofitting existing engines.
In practice, the injection of gaseous fuel, e.g. hydrogen, propane, natural gas and the like into an engine, has typically been accomplished in two alternative methods. The first method involves introducing the fuel through an inlet air passage, e.g. gas mixer, where the vacuum of the engine draws the air-fuel mixture into the cylinder. The second method involves injecting the fuel directly into the cylinder of the engine, e.g. direct injection. Each of these methods, as practiced with the prior art, have their own disadvantages with respect to introducing hydrogen to an engine.
Various mixer apparatus have been proposed for mixing gaseous fuel with air entering the engine. There is a considerable amount of prior art in this field, however, much of the effort has concentrated on the addition of gaseous fuels such as natural gas, methane gas, liquid petroleum gas or others. However, due to the combustive properties of hydrogen and the widely varying loads of vehicles this method often results in a problem referred to as “flashback”. Flashback occurs when the mixture of hydrogen and oxygen ignite in the intake manifold of the engine causing a severe explosion.
Alternatively, hydrogen may be injected into the combustion chamber using direct injection. When hydrogen is injected directly into the combustion chamber of an engine, the injection usually takes place during the intake or compression stroke either before and/or during the combustion process. Controlling the amount of the gaseous fuel entering the combustion chamber has proven difficult with this method, generally resulting in unacceptable torque characteristics and output from the engine.
Accordingly, a cost effective, reliable and versatile system for improving combustion and reducing emissions from hydrogen and/or gasoline fuels that can be easily adapted to existing gasoline engines without extensive modification would satisfy a long felt need in the art.